Hearing aids are technical aids which compensate for congenital or acquired losses in auditory function that do not respond to causal treatment. Hearing aids amplify and modulate the sound, in other words the acoustic signal, upstream of the actual sensory organ of the ear, the inner ear. Constructed of a microphone, amplifier, power source and receiver, various types of aid are available.
FIG. 1 shows a diagrammatic illustration of a so-called behind-the-ear (BTE) hearing aid. This concerns a hearing aid 1 which is worn behind the pinna. The amplified sound is routed into the external acoustic meatus via a carrying hook 2 (also called a hook or elbow fitting or angle piece), a sound tube (not shown) and an earpiece (not shown) principally manufactured from transparent plastic. Depending on the configuration the BTE device 1 can have a volume control 4 and a switch 5 for switching on and off as well as for selecting an inductive operating mode.
The carrying hook 2 has a sound channel 3, with which the sound generated by a receiver is routed to the sound tube, which can be pushed over a swelling in the carrying hook 2, said swelling having the shape of a truncated cone.
Such carrying hook/sound tube arrangements are frequently provided with acoustic dampers, in order to achieve improvements in sound, for example by smoothing sound channel resonances and/or achieving a frequency response perceived as pleasant.
Different damper arrangements for hearing aids are known from the prior art. In the example in FIG. 1 a damper 6 is introduced into the end or the tip of the carrying hook 2. FIGS. 2a and 2b show such a damper. In such an arrangement the diameter of the membrane, which produces the acoustic damping, is generally only 1.4 mm, since the tip of the carrying hook 2 is tailored to the sound tube, which generally has an internal diameter of 2 mm, and since moreover the membrane is held by a metal sleeve, which for its part limits the effective diameter. It would however be desirable for the diameter of the membrane to be as large as possible in order to obtain as large as possible an acoustically effective surface area.
An arrangement is known from DE 201 14 523 U1 in which the damper is introduced into a lateral slit in the carrying hook and is fixed there by the sound tube which is then pushed over it. While such an arrangement does away with the problem addressed above of the diameter being too small, it is expensive in design terms, and if the sound tube is accidentally removed from the carrying hook the damper—as also in the arrangement according to FIG. 1—can easily get lost.
Different filter arrangements are known from U.S. Pat. No. 4,677,675 which are accommodated in the carrying hook 2. While such filters can also serve as dampers, they are however much too expensive for this comparatively easy purpose and require the carrying hook to have a certain volume, which runs counter to the miniaturization being striven for.